Making bath bombs is a fantastic chemistry project that doubles as a spa treat. The "fizz" comes from a simple acid-base reaction between citric acid and baking soda. When dry, they are stable; when they hit the water, they react to release carbon dioxide gas.

Here is a recipe for beginners. Please note this is an AI generated recipe and is very different to our own recipe which is used in our Cosmetic Safety Assessments for those who wish to make and sell bath bombs.

All ingredients are available on The Crafters Shop Website. 

The Ingredients & Equipment

This batch makes about 3–4 standard-sized bath bombs.

Tools: Mixing bowl, whisk, and bath bomb moulds (or even a muffin tin/ice cube tray).

Step-by-Step Instructions

1. Mix the Dry Ingredients

Whisk the baking soda, citric acid, and cornflour in a large bowl. Ensure there are no lumps; the mixture should look like fine sand.

2. Prepare the Wet Ingredients

In a separate small jar, whisk your oil and essential oils. If you are using colouring, add it here too although be aware that mica or food colouring for this very basic recipe may stain your bath.  If you do wish to add colour, aim for a pastel shade and use sparingly.

3. Combine (Slowly!)

Slowly pour the oil mixture into the dry ingredients while mixing constantly. Using your hands may be easier.

Critical Tip: If the mixture starts to foam or fizz, you’re adding the liquid too fast. Slow down!

4. The "Sand" Test

Now, use your spray bottle to add tiny amounts of water. After every 2–3 spritzes, mix with your hands. You are looking for the texture of damp sand.

• The Test: Squeeze a handful in your palm. If it holds its shape without crumbling, it’s ready. If it falls apart, add one more spritz of water.

5. Mould the Bombs

Pack the mixture tightly into your moulds. If using spherical moulds, (Not the easiest starter mould) overfill each half slightly and press them together firmly—don't twist, just press.

6. Dry and Set

Let the bath bombs sit in the moulds for at least 24 hours in a cool, dry place.  If you try to remove them too early, they may crumble. Once hard, pop them out and store them in an airtight jar to keep moisture away. My own advice is that if left in the mould, any amount of activation, which happens to all of us, may make removing the bath bomb really difficult, you would also need more than one mould, with care the bath bomb should release immediately, however this is why we have bath dust, it takes care of all of the broken bath bombs ever made.